The present invention is related to an electronic component mounting apparatus and an electronic component mounting method, which mount an electronic component on a board.
In electronic component mounting apparatus, mounting operations are repeatedly carried out in which electronic components derived from electronic component supply units are held by mounting heads and then are mounted on boards. In these mounting operations, since the electronic components are required to be positioned on the boards in higher precision, such positioning methods have been widely employed. In the positioning methods, while both the electronic components being held by the mounting heads and positions of mounting points on the boards are optically detected, the electronic components and the boards are relatively positioned with each other based upon position detecting results.
In such an optical position detecting operation, two images acquired by photographing an electronic component and a board by a camera are processed by way of an image recognizing process operation so as to execute this optical position detecting operation. In this image recognizing process operation, since both the electronic component and the mounting position of the board are recognized based upon different images, in order that the electronic component is positioned with respect to the mounting point of the board in higher precision, it is very important to correctly acquire a relative positional relationship between these two images with respect to an optical coordinate system.
To this end, such a camera of upper/lower visual-field directions has been employed (for example, see Japanese Laid-open Patent Application No. 2001-77592). In this camera, both a board recognizing camera whose photographing visual-field direction is downwardly directed and an electronic component recognizing camera whose photographing visual-field direction is upwardly directed are constructed in an integral form. When this camera is used, generally speaking, under such a condition that a mounting head which holds an electronic component is positioned over a board, this camera is advanced to a space formed between the mounting head and the board, and then simultaneously acquires both an image as to a mounting point of the board and an image as to the electronic component held by the mounting head. As a result, a relative positional relationship between a photographing visual field along the upper direction and a photographing visual field along the lower direction is continuously maintained, so that high-precision position detecting operations may be realized.
However, in the above-described prior art, since there is such a restriction that the camera must be positioned between the board and the mounting head, a limitation is made in shortening of tact time of the mounting operation. In other words, since the above-described position detecting operation is carried out with respect to each of the electronic components mounted by the mounting head, in a mounting operation of one electronic component, both an operation for advancing the camera just under the mounting head so as to acquire images, and another operation for evacuating the camera from the space over the board in order to avoid interference occurred between the camera and the descending operation of the mounting head after the images have been acquired are required to be carried out every time the above-described mounting operation of one electronic component is performed.
Also, when the mounting head which has held the electronic component performs the mounting operation over the board, an elevation height of the mounting head must be set to a low value as being permitted as possible in order that the operation time thereof may be desirably shortened. However, as previously explained, since such a clearance by which the camera can be advanced must be secured, the descent amount of the mounting head required in the mounting operation cannot be decreased. As previously explained, in the conventional electronic component mounting apparatus, the superior mounting position precision can be hardly compatible with the electronic component mounting work executed in the high efficiency.